The invention lies in the field of fluid line couplings and particularly couplings using push-on fittings of the type shown in Ford Motor Company's U.S. Pat. No. 4,055,359. My invention provides a unique axially split-clamp which improves the sealing of couplings utilizing push-on fittings.
When the Ford Motor Company began using its patented push-on fittings with garter-type coil springs on its vehicle air conditioning fluid lines and fuel lines, it created a vehicle service industry problem that until recently could be solved only by buying and installing new Ford-made components. The problem continues to be acute due to the high incidence of failure of the O-rings used to seal the connection between the push-on fitting and the pipe to which it is coupled.
The end of the push-on fitting is flared and sized to fit into a cage which houses a garter-type coiled spring. The fitting is pushed onto the pipe and over the O-rings on the end of the pipe until the flared end of the fitting enters the cage and forces the coil spring over the flared end of the pipe and down to encircle the fitting. The spring now prevents the fitting from being pulled out of the cage. Fluid under pressure is sealed within the line by the O-rings between the pipe and the push-on fitting.
Push-on fittings are used to connect a flexible hose to the condenser, the evaporator, the accumulator and the compressor of the air conditioning system and also for connections to the gasoline tank and the carburetor of the vehicle's fuel system.
The fluid lines of vehicle air conditioning systems conventionally operate with line pressures of at least 100 p.s.i. and, at high ambient temperatures, line pressures of 300 p.s.i. are not uncommon. These pressures put severe strain upon the seal between the push-on fitting and the pipe to which the fitting is coupled.
The high incidence of O-ring failures results from high line pressures and the fact that the push-on fitting is usually on one end of a length of flexible hose. Constant vibration and movement of the flexible hose during running of the vehicle's engine and the vehicle itself forces the fitting to move back and forth transverse to its axis, causing wear and eventual rupture of the seal between the O-rings and the inner surface of the push-on fitting.
The locking assembly shown and described in my earlier application Ser. No. 002,437 filed Jan. 12, 1987 pushes the flared end of the fitting firmly against the inside of the cage, holds the push-on fitting in axial alignment with the pipe to which the fitting is coupled and, in addition, puts a 360.degree. inwardly directed pressure on the seal between the O-rings and the inner surface of the fitting. That assembly includes two major components: a male fitting and a uniquely shaped locking nut, both of which are axially sawed apart into two mirror-image halves.
The unique locking assembly described in my earlier application Ser. No. 002,437 does a perfect long term job of preventing leaking and eventual failure of the seal provided by the O-rings of the push-on coupling.
Instead of using the aforementioned locking assembly, some improvement in the sealing of couplings utilizing Ford push-on fittings can be achieved by using my unique axially split clamp. Each half of my axially split clamp contains a semi-annular recess designed to fit snugly over the cage housing the coiled spring of the pipe and an adjacent semi-circular surface having the same diameter as the outer surface of the push-on fitting adjacent the cage. The two halves of the clamp each contain a pair of mutually aligned threaded holes sized to receive a pair of screws for joining the two halves together.
In order to prevent engine vibration and vehicle movement from eventually rupturing the seals maintained by the two O-rings of the coupling, the two halves of my axially split clamp are placed around the coupled pipe and push-on fitting. The semi-annular recesses of the two clamp halves are placed over the cage of the pipe and the clamps semi-circular surfaces are engaged with the outer surface of the push-on fitting. Two screws are then threaded into the two aligned holes in the clamp halves to draw the two halves securely together, thereby locking the couplings' pipe and fitting into axial alignment.